Nano-gypsum in low dose improves the physicochemical properties of saline-sodic soil

Increased Na+ ions negatively affect soil physicochemical characteristics. We ran a pot incubation experiment for 2 months and a leaching experiment for another 2 months to monitor the effects of nano-gypsum (NG, <100 nm) in low affordable doses on improving saline-sodic soil physicochemical characteristics. Treatments included a control (CK), conventional gypsum (CG; <= 0.5 mm) at 100% CG requirement (8.9 t ha(-1): CGR), and three low doses of NG (240, 480 and 960 kg ha(-1) = 2.7%, 5.4% and 10.8% of the CGR). Both applications of NG at 10.8% of CGR and the CG at 100% of CGR followed by leaching had the best effect and performed almost equally. However, the use of 960 kg NG ha(-1) had the most pronounced effect, where it decreased the bulk density (16.4%) and increased stable soil structure (46.2%). Also, the soil hydraulic conductivity increased by approximately 2.4 times, which helped increase the Na-removal efficiency by 68.9%. Moreover, it decreased soil reaction, electrical conductivity and exchangeable-Na percentage by 15.9%, 39.7% and 71.4% compared to the CK, respectively. Therefore, the NG may introduce novel and alternative application strategy that allows for lower application rate with an adequate gypsum requirement.